/*
 * @(#)$Id: codetemplate_xbird.xml 943 2006-09-13 07:03:37Z yui $
 * 
 * Copyright 2006-2008 Makoto YUI
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 * 
 * Contributors: Makoto YUI - initial implementation
 */
package jacky.lanlan.song.concurrent;

import java.util.concurrent.atomic.AtomicInteger;

/**
 * 
 * @author Makoto YUI (yuin405+xbird@gmail.com)
 */
public abstract class AtomicUtils {
	
	public static boolean tryIncrementIfLessThan(final AtomicInteger capacity, final int atmost) {
		int capa;
		do {
			capa = capacity.get();
			if (capa >= atmost) { return false; }
		} while (!capacity.compareAndSet(capa, capa + 1));
		return true;
	}
	
	public static int tryIncrementAndGetIfLessThan(final AtomicInteger capacity, final int upperbound) {
		for (;;) {
			final int current = capacity.get();
			if (current >= upperbound) { return upperbound; }
			final int next = current + 1;
			if (capacity.compareAndSet(current, next)) { return next; }
		}
	}
	
	public static boolean tryIncrementIfGreaterThan(final AtomicInteger capacity, final int least) {
		int capa;
		do {
			capa = capacity.get();
			if (capa <= least) { return false; }
		} while (!capacity.compareAndSet(capa, capa + 1));
		return true;
	}
	
	public static boolean tryDecrementIfGreaterThan(final AtomicInteger capacity, final int least) {
		int capa;
		do {
			capa = capacity.get();
			if (capa <= least) { return false; }
		} while (!capacity.compareAndSet(capa, capa - 1));
		return true;
	}
	
	public static int tryDecrementAndGetIfGreaterThan(final AtomicInteger capacity, final int least) {
		for (;;) {
			final int current = capacity.get();
			if (current <= least) { return current; }
			final int next = current - 1;
			if (capacity.compareAndSet(current, next)) { return next; }
		}
	}
	
}
